I am sure the caffeine helped but I was getting caffeine in the form of coffee with lunch on the previous rides, so I would not say that it was a change in the control group. The real change was the gel and more intake of it. I guess I could of gotten the same benefit with cliff bars but the gel is quicker to eat and my body seems to process it quicker. I did a second series of hills and was hurting ate a gel and within 15+/- minutes felt like I had gotten a second wind. I have done that before and already know the benefit but the fact that I felt fine after the ride was the big plus. I also feel good today and will do a short 30+/- mile ride.